Audio-Technica ATH-M50x
Flat response, closed-back, comfortable for long sessions. The workhorse for focused work.
The ATH-M50x is a studio monitoring staple for a reason — the frequency response is flat enough that what you hear is actually there. I didn't buy these for music listening; I bought them for design reviews, audio passes on project videos, and long work sessions where I needed isolation without the fatigue that active cancellation headphones bring.
Five years in and they've held up well. The headband padding has compressed slightly but the ear cups are still comfortable for three to four hour sessions. I replaced the stock cable with a coiled version that sits better at the desk and doesn't tangle across the keyboard.
The closed-back design does real isolation without batteries — useful in cafés or anywhere I don't want to think about charge levels. The passive isolation handles most environments fine.
The sound profile rewards critical listening. It's not flattering — it won't hype your music. What it does is reveal detail, which is exactly what I need from a work headphone. Commute and casual listening is a different tool.